Electrical Efficiency Measurement for Data Centers

Elect rical Efficiency
Meas urement for
Data Centers


By Neil Rasmussen
White Paper #154
Revision 1


Executive Summary
Data center electrical efficiency is rarely planned or managed. The unfortunate result is that
most data centers waste substantial amounts of electricity. Today it is both possible and
prudent to plan, measure, and improve data center efficiency. In addition to reducing
electrical consumption, efficiency improvements can gain users higher IT power densities
and the ability to install more IT equipment in a given installation. This paper explains how
data center efficiency can be measured, evaluated, and modeled, including a comparison of
the benefits of periodic assessment vs. continuous monitoring.




©2007-2008 American Power Conversion. All rights reserved. No part of this publication may be used, reproduced, photocopied, transmitted, or stored in any retrieval system of any nature, without the written permission of the copyright owner. www.apc.com WP154 Rev 1 2Introduction
In today's environment, it is good public policy and good business to consider the options to control data center energy consumption. A 1MW high availability data center can consume $20,000,000 of electricity over its lifetime. Recent articles suggest that for some customers the cost of electricity is greater than the cost of IT hardware. Many companies are beginning to consider the carbon consumption of their ongoing operations and realizing that data centers are significant contributors to the environmental burden of business and industry. Research by APC-MGE and others is showing that efficiency varies widely across similar data centers, and - even more significant - the actual efficiencies of real installations are well below the practical achievable best-in-class values. In this paper, we will focus on the power consumption and efficiency of data center power and cooling infrastructure, which consumes 50% or more of the electrical power in a typical installation. The power consumption and efficiency of the actual IT equipment supported by the power and cooling infrastructure, while critically important to overall energy use, is not the subject of this paper (Figure 1). Figure 1 - Efficiency of power and cooling is the subject of this paper
POWER to IT loads PDU COOLING to IT loads
PDU
UPS CoolingsystemPDU
PDUPPOOWWEERR CCOOOOLLIINNGG EEffffiicciieennccyy EEffffiicciieennccyyEfficiency of IT loads is important, but not the subject of this paper You can't control what you can't measure. The first problem users face is that they don't have data regarding the performance of their facilities. In addition, even if they do have data, they don't know how to evaluate it. They don't know how to compare or benchmark their performance to the efficiency of other similar facilities. They don't even know how to compare the actual data to the as-designed performance they should expect from their facilities. In 2008, most users don't have efficiency data - and even if they did, they wouldn't know how to act on it. Solving these problems requires:
. A standard language for describing data center efficiency
©2007-2008 American Power Conversion. All rights reserved. No part of this publication may be used, reproduced, photocopied, transmitted, or stored in any retrieval system of any nature, without the written permission of the copyright owner. www.apc.com WP154 Rev 1 3. A standard method for measuring data center efficiency . A standard method for specifying data center efficiency . A standard method for analyzing data center efficiency and determining the contributors to inefficiency . Benchmark data relating to efficiency . Efficiency modeling tools to assess proposed improvements or alternative designs Fortunately, there are no fundamental practical or technical barriers to achieving these objectives. In fact, this paper asserts that data center operators should consider the management of efficiency as a top priority for both existing and new data centers. This paper addresses all of the above issues, except the specification of data center efficiency.
The Concept of Data Center Electrical Efficie... [download for more]